Intelligent multi-stage pressure-reducing, water-draining and seepage-stopping device for deep foundation pit construction and construction method

Abstract

The invention discloses an intelligent multi-stage pressure reducing, water draining and seepage stopping device for deep foundation pit construction and a construction method. The intelligent multi-stage pressure reducing, water draining and seepage stopping device comprises a multi-stage dewatering well system, a pit bottom inverted filter-cushion layer-compacted soil water stopping layer structure, a digital water pressure sensing system and an intelligent control unit. The multiple stages of precipitation wells are arranged along the bottom and the pit edge of the foundation pit and are linked with the digital water pressure sensing system, so that the underground water pressure can be monitored in real time; when monitoring data reach a set threshold value, the intelligent control unit automatically opens the corresponding graded pressure relief channel, and dynamic partitioned pressure reduction is achieved. According to the device and the construction method, on the premise that the stability of an enclosure structure is not affected, the pit bottom upheaval and sudden gushing risks are effectively reduced, the device and the construction method are suitable for high-water-pressure foundation pit construction of river-crossing tunnels, subway river-crossing sections, ultra-deep underground spaces and the like, intelligent control and graded pressure relief of underground water pressure are achieved, the construction safety is high, and operation is convenient and fast.

Description

Technical Field

[0001] This invention relates to the field of deep foundation pit construction technology, and in particular to an intelligent multi-stage pressure reduction, drainage and seepage prevention device and construction method for high water pressure river-crossing tunnels and ultra-deep underground space foundation pit construction. Background Technology

[0002] In the construction of river-crossing tunnels and underground spaces, deep foundation pits often face high water head seepage pressure and complex geological conditions. Soft soil, sand, or aquifers may exist at the bottom and edges of the pit. Insufficient drainage or inadequate water-stopping measures during construction can cause bottom heave, localized water inrush, or overall seepage damage, seriously threatening the stability of the retaining structure and construction safety. Traditional construction methods mainly rely on single-stage depressurization wells, temporary drainage ditches, or passive water-stopping structures, but these methods have the following limitations: First, drainage efficiency is low and distribution is uneven. Single-stage depressurization wells or simple drainage ditches are insufficient to form an effective zoned drainage network at the bottom and sides of the pit. When the water pressure distribution is uneven, the local water head may still be too high, leading to sudden water inrush or local pit instability.

[0003] Second, there is a lack of real-time monitoring and control capabilities. Most existing drainage and water-stopping measures are passively controlled, lacking water pressure sensors and intelligent control systems. This makes it impossible to dynamically adjust the drainage and water-stopping status, which can easily lead to water pressure fluctuations affecting the foundation pit structure and make it difficult to respond in a timely manner.

[0004] Third, construction safety is insufficient. Under high water head conditions, traditional drainage methods may lead to excessive local precipitation or excessive soil settlement, increasing the risks of retaining structure and foundation pit construction.

[0005] Therefore, developing an intelligent multi-stage pressure reduction drainage and seepage prevention device that can perform graded drainage, intelligent monitoring, dynamic water pressure control, and improve the safety of foundation pits has significant engineering application value. Summary of the Invention

[0006] This invention addresses the aforementioned problems in existing technologies by proposing an intelligent multi-stage pressure-reducing drainage and seepage-stopping device and construction method for deep foundation pit construction. By constructing a network of zoned pressure-reducing wells and dewatering wells, it achieves graded drainage at the pit bottom and edges. Combined with a bottom filter layer, sand cushion layer, and compacted soil water-stopping structure, it effectively prevents seepage damage to the foundation pit. Simultaneously, through the linkage of water pressure sensors, a data acquisition system, and an intelligent control unit, it achieves real-time monitoring and dynamic control of groundwater pressure, enabling adjustment of drainage volume and zoned start-up and shutdown at different construction stages, thus achieving precise management of the foundation pit's hydraulic conditions.

[0007] The technical solution adopted in this invention is: an intelligent multi-stage decompression, drainage and seepage prevention device for deep foundation pit construction, including a multi-stage dewatering well system, a pit bottom water-stopping structure, a digital water pressure sensing system, an intelligent control unit and a drainage and collection system; The multi-stage dewatering well system includes multi-stage dewatering wells installed along the bottom of the pit and pressure-reducing wells installed at the edge of the pit, forming a zoned dewatering network and connected to a digital water pressure sensing system. The pit bottom water-stopping structure consists of a filter layer, a cushion layer, and a compacted soil water-stopping layer laid from bottom to top, which are used to prevent fine particles from penetrating and provide a stable water-stopping barrier. The digital water pressure sensing system includes a water pressure sensor, a data acquisition module, and control software. The water pressure sensor is deployed at each level of dewatering well and at the bottom and edge of the pit to record the water pressure at each monitoring point in real time and generate alarm signals. The intelligent control unit is connected to the digital water pressure sensing system and determines whether to activate the various levels of pressure relief functions based on the monitoring data to achieve dynamic water pressure regulation. The drainage and collection system is the main drainage channel system, including a collection well and a collection pipeline connected to the dewatering wells at all levels; the reinjection pipeline is interconnected with the pressure layer through a water-stop valve, and the water-stop valve is electrically connected to the intelligent control unit. The quantitative reinjection of groundwater is achieved by closing the water-stop valve.

[0008] The drainage and reinjection pipelines are automatically controlled by a water pressure sensor and an intelligent control unit to switch between groundwater discharge and reinjection modes, thereby achieving orderly discharge or quantitative reinjection of groundwater.

[0009] Furthermore, the multi-stage dewatering well system is divided into at least three layers: a pit bottom dewatering layer, a pit edge depressurization layer, and an outer recharge dewatering layer. Each layer of the dewatering system can be opened or closed independently to achieve graded pressure relief.

[0010] Furthermore, the spacing of the multi-stage dewatering well system is designed according to the width and depth of the pit. The spacing between the dewatering wells at the bottom of the pit is 1-3m, and the spacing between the dewatering wells at the edge of the pit is 2-4m, to ensure uniform distribution and effective pressure relief.

[0011] Furthermore, the multi-stage dewatering well system is made of steel pipes, the pipe diameter of which can be selected according to the water head of the foundation pit and the soil seepage conditions. Adjustable valves are installed at the ends of the multi-stage dewatering well system to control the drainage flow.

[0012] Furthermore, the filter layer is gravel with a particle size of 5-15mm, the cushion layer is a medium sand layer, and the compacted soil water-stopping layer is a clay layer mixed with bentonite. The thickness and material ratio can be adjusted according to the water head and soil conditions of the foundation pit.

[0013] Furthermore, the intelligent control unit includes a PLC or embedded controller, supporting remote monitoring and data storage, and adjusting the tiered pressure relief strategy in real time according to the construction progress. The intelligent control unit can determine groundwater pressure through preset monitoring point water pressure thresholds and automatically control the opening and closing of corresponding dewatering wells to achieve dynamic zonal pressure relief.

[0014] Furthermore, the water pressure threshold at the monitoring point can be preset to 60% to 80% of the maximum water pressure at the bottom of the pit. When the water pressure exceeds the threshold, the corresponding precipitation section will be automatically activated, and when it is below the threshold, it will be deactivated to prevent excessive precipitation from causing land subsidence.

[0015] Furthermore, the drainage and collection system and the reinjection pipeline are equipped with adjustable valves to achieve precise control of the discharge and reinjection flow rates and maintain a stable groundwater level.

[0016] The device of this invention is suitable for high-water-head foundation pits such as river-crossing tunnels, subway river-crossing sections, and ultra-deep underground spaces, with a foundation pit excavation depth ≥20m and a static water head pressure ≥150kPa.

[0017] The construction method of the above-mentioned intelligent multi-stage pressure reduction, drainage and seepage prevention device for deep foundation pit construction includes the following steps: Step 1: Excavation and support of the foundation pit: Determine the groundwater level and seepage parameters, and complete the excavation of the foundation pit and the construction of the retaining structure; Step 2: Dewatering system layout: Set up multi-stage dewatering wells / dewatering wells at the bottom and sides of the pit to form a zoned drainage network; Step 3: Construction of the pit bottom water-stop layer: From bottom to top, lay the filter layer, the cushion layer and the compacted soil water-stop layer in sequence; Step 4: Installation of digital water pressure sensing system: Install water pressure sensors at key locations in each level of dewatering well and foundation pit, and connect them to the intelligent control unit; Step 5: Staged pressure relief commissioning: Set water pressure thresholds based on monitoring data. When the water pressure at the monitoring point reaches the threshold, the intelligent control unit automatically opens the corresponding dewatering well to achieve dynamic zoned pressure relief. Step 6: Operation and Maintenance: Monitor water pressure changes in real time, and adjust parameters and recharge as necessary to ensure the stability of the foundation pit and the balance of the groundwater environment.

[0018] Furthermore, in step 5, the dewatering wells are opened or closed sequentially according to the order of the pit bottom, pit edge and surrounding dewatering layer to achieve zoned control.

[0019] The construction method of this invention allows for dynamic adjustment of the number of dewatering wells, their flow rate, and threshold settings based on monitoring data to adapt to different geological conditions and water head changes in foundation pits. It enables multi-stage pressure reduction and seepage control operations during a single foundation pit excavation, eliminating the need for repeated construction and saving construction time.

[0020] The beneficial effects of this invention are: First, the multi-level zoned pressure reduction design enables dynamic control of water pressure at the bottom and sides of the pit, reducing the risk of localized surges and pit bottom heave.

[0021] Secondly, the reverse filter layer-sand cushion layer-compacted soil water-stopping structure improves the stability of the foundation pit bottom and prevents soil seepage damage.

[0022] Third, the digital water pressure sensing system works in conjunction with the intelligent control unit to achieve real-time monitoring and dynamic control of water pressure, reducing the risk of manual operation.

[0023] Fourth, the drainage, water collection and recharge system can precisely control groundwater discharge and recharge, avoiding land subsidence caused by excessive precipitation.

[0024] Fifth, this invention is applicable to the construction of river-crossing tunnels, subway sections crossing rivers, and ultra-deep underground spaces. It is easy to operate, safe and reliable in construction, and can effectively improve the safety and efficiency of deep foundation pit construction. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall device of the present invention; Explanation of the labels in the diagram: 1-Pit retaining structure; 2-External pressure-reducing well; 3-Internal multi-stage dewatering well; 4-Compacted soil water-stopping layer; 5-Subbase layer; 6-Filter layer; 7-Water pressure sensor; 8-Intelligent control unit; 9-Drainage and collection system; 10-Recharge pipeline; 11-Water stop valve. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Example

[0027] Reference Figure 1 This embodiment focuses on the construction of deep foundation pits for river-crossing tunnels, including foundation pit retaining structure 1. The excavation depth of the foundation pit is approximately 25-30m, and the hydrostatic head pressure is approximately 180-200kPa. The construction method is as follows. First, multi-stage dewatering wells (3) inside the pit and pressure-reducing wells (2) outside the pit are installed at the bottom and edge of the pit. The spacing between the dewatering wells at the bottom of the pit is about 2m, and the spacing between the dewatering wells at the edge of the pit is about 3-4m. The dewatering wells are made of pressure-resistant polyethylene pipes or steel pipes, and the pipe ends are equipped with adjustable valves to control the drainage flow according to the groundwater pressure and construction progress.

[0028] Secondly, a water-stopping structure is laid at the bottom of the foundation pit. The filter layer 6 (10-15cm thick), the cushion layer 5 (20-25cm thick), and the compacted soil water-stopping layer 4 (approximately 30cm thick) are constructed sequentially to ensure the overall stability of the pit bottom and prevent fine particles from being lost with drainage. The filter layer 6 and the cushion layer 5 serve to bear pressure and disperse hydraulic forces, while the compacted soil water-stopping layer 4 forms a continuous hydraulic barrier.

[0029] Next, a digital water pressure sensing system is installed. Water pressure sensors 7 are deployed at various levels of dewatering wells and key pit bottom locations. The sensors are connected to the data acquisition module and intelligent control unit 8. Before construction, a water pressure threshold is set. When the monitored water pressure exceeds the set value, the control unit automatically opens the corresponding dewatering valve to achieve zoned drainage; when the water pressure is below the threshold, the valve is closed to avoid excessive drainage.

[0030] During construction, the drainage and collection system 9 concentrates groundwater into the collection well, and can replenish groundwater around the pit by opening the stop valve 11 to the recharge pipeline 10, thus achieving a water level balance in the foundation pit. The intelligent control system can adjust the drainage and recharge volumes in real time according to the construction stage.

[0031] Throughout the construction process, the synergistic effect of multi-level zoned pressure reduction, pit bottom water-stopping structure, intelligent monitoring and control system, and drainage and recharge system ensures the safety, controllability, and efficiency of high-head deep foundation pit construction.

[0032] It should be understood that the present invention is not limited to the embodiments, methods, structures, and precise structures shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. An intelligent multi-stage pressure reduction, drainage, and seepage prevention device for deep foundation pit construction, characterized in that: This includes a multi-stage dewatering well system, a pit bottom sealing structure, a digital water pressure sensing system, an intelligent control unit, and a drainage system; The multi-stage dewatering well system includes multi-stage dewatering wells installed along the bottom of the pit and pressure-reducing wells installed at the edge of the pit, forming a zoned dewatering network and connected to a digital water pressure sensing system. The pit bottom water-stopping structure consists of a filter layer, a cushion layer, and a compacted soil water-stopping layer laid from bottom to top, which are used to prevent fine particles from penetrating and provide a stable water-stopping barrier. The digital water pressure sensing system includes a water pressure sensor, a data acquisition module, and control software. The water pressure sensor is deployed at each level of dewatering well and at the bottom and edge of the pit to record the water pressure at each monitoring point in real time and generate alarm signals. The intelligent control unit is connected to the digital water pressure sensing system and determines whether to activate the various levels of pressure relief functions based on the monitoring data to achieve dynamic water pressure regulation. The drainage and collection system is the main drainage channel system, including a collection well and a collection pipeline connected to the dewatering wells at all levels; the reinjection pipeline is interconnected with the pressure layer through a water-stop valve, and the water-stop valve is electrically connected to the intelligent control unit. The quantitative reinjection of groundwater is achieved by closing the water-stop valve.

2. The intelligent multi-stage pressure reduction, drainage and seepage prevention device for deep foundation pit construction according to claim 1, characterized in that: The multi-stage dewatering well system consists of at least three layers: a pit bottom dewatering layer, a pit edge depressurization layer, and an outer recharge dewatering layer. Each layer of the dewatering system can be opened or closed independently to achieve graded pressure relief.

3. The intelligent multi-stage pressure reduction, drainage and seepage prevention device for deep foundation pit construction according to claim 2, characterized in that: The spacing between the bottom dewatering wells in the multi-stage dewatering well system is 1-3m, and the spacing between the edge dewatering wells is 2-4m.

4. The intelligent multi-stage pressure reduction, drainage and seepage prevention device for deep foundation pit construction according to claim 3, characterized in that: The multi-stage dewatering well system is made of steel pipes, and adjustable valves are installed at the ends of the multi-stage dewatering well system to control the drainage flow.

5. The intelligent multi-stage pressure reduction, drainage and seepage prevention device for deep foundation pit construction according to claim 4, characterized in that: The filter layer is composed of gravel with a particle size of 5-15mm, the cushion layer is composed of medium sand, and the compacted soil water-stopping layer is composed of clay mixed with bentonite.

6. The intelligent multi-stage pressure reduction, drainage and seepage prevention device for deep foundation pit construction according to claim 5, characterized in that: The intelligent control unit includes a PLC or embedded controller, which supports remote monitoring and data storage. It adjusts the graded pressure relief strategy in real time according to the construction progress. The intelligent control unit judges the groundwater pressure by preset monitoring point water pressure thresholds and automatically controls the opening and closing of the corresponding dewatering wells to achieve dynamic zoned pressure relief.

7. The intelligent multi-stage pressure reduction, drainage and seepage prevention device for deep foundation pit construction according to claim 6, characterized in that: The water pressure threshold at the monitoring point is preset to 60% to 80% of the maximum water pressure at the bottom of the pit. When the water pressure exceeds the threshold, the corresponding precipitation section will be automatically activated, and when it is below the threshold, it will be deactivated to prevent excessive precipitation from causing land subsidence.

8. The intelligent multi-stage pressure reduction, drainage and seepage prevention device for deep foundation pit construction according to claim 7, characterized in that: The drainage and collection system and the reinjection pipeline are equipped with adjustable valves to achieve precise control of the discharge and reinjection flow rates.

9. The construction method of the intelligent multi-stage pressure reduction, drainage and seepage prevention device for deep foundation pit construction according to claim 1, 2, 3, 4, 5, 6, 7 or 8, characterized in that: Includes the following steps: Step 1: Excavation and support of the foundation pit: Determine the groundwater level and seepage parameters, and complete the excavation of the foundation pit and the construction of the retaining structure; Step 2: Dewatering system layout: Set up multi-stage dewatering wells / dewatering wells at the bottom and sides of the pit to form a zoned drainage network; Step 3: Construction of the pit bottom water-stop layer: From bottom to top, lay the filter layer, the cushion layer and the compacted soil water-stop layer in sequence; Step 4: Installation of digital water pressure sensing system: Install water pressure sensors at key locations in each level of dewatering well and foundation pit, and connect them to the intelligent control unit; Step 5: Staged pressure relief commissioning: Set water pressure thresholds based on monitoring data. When the water pressure at the monitoring point reaches the threshold, the intelligent control unit automatically opens the corresponding dewatering well to achieve dynamic zoned pressure relief. Step 6: Operation and Maintenance: Monitor water pressure changes in real time, and adjust parameters and recharge as necessary to ensure the stability of the foundation pit and the balance of the groundwater environment.

10. The construction method of the intelligent multi-stage pressure reduction, drainage and seepage prevention device for deep foundation pit construction according to claim 9, characterized in that: In step 5, the dewatering wells are opened or closed sequentially according to the order of pit bottom, pit edge and outer dewatering layer to achieve zoned control.

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